title: Chronic traumatic encephalopathy in sport: a systematic review.
abstract: OBJECTIVE
  To provide a critical review of chronic traumatic encephalopathy (CTE) by considering the range of clinical presentations, neuropathology and the strength of evidence for CTE as a distinct syndrome.
  
  
  METHODS
  Seven electronic databases were searched using a combination of MeSH terms and key words to identify relevant articles.
  
  
  METHODS
  Specific inclusion and exclusion criteria were used to select studies for review. Data extracted where present included study population, exposure/outcome measures, clinical data, neurological examination findings, cognitive assessment, investigation results and neuropathology results.
  
  
  RESULTS
  The data from 158 published case studies were reviewed. Critical differences between the older descriptions of CTE (the 'classic' syndrome) and the recent descriptions (the 'modern' syndrome) exist in the age of onset, natural history, clinical features, pathological findings and diagnostic criteria, which suggests that modern CTE is a different syndrome. The methodology of the current studies does not allow determination of aetiology or risk factors.
  
  
  CONCLUSIONS
  The clinicopathological differences between the 'classic' CTE syndrome and the 'modern' syndrome suggest that the new syndrome needs a different nomenclature. Further research is required to clearly define the clinical phenotype of the modern CTE syndrome and establish the underlying aetiology. Future research needs to address these issues through large-scale, prospective clinicopathological studies.
authors.affiliation: Centre for Translational Neuroscience and Mental Health, School of Medicine and Public Health, University of Newcastle, , Callaghan, New South Wales, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Gardner
authors.forename: Grant L
authors.initials: GL
authors.lastname: Iverson
authors.forename: Paul
authors.initials: P
authors.lastname: McCrory
mesh_terms: D017668:Age of Onset; D001265:Athletic Injuries / Q000209:etiology / Q000473:pathology*; D001914:Boxing / Q000293:injuries; D001924:Brain Concussion / Q000209:etiology / Q000473:pathology*; D020208:Brain Injury, Chronic / Q000209:etiology / Q000473:pathology*; D042241:Early Diagnosis; D006801:Humans; D010641:Phenotype; D013577:Syndrome; D009626:Terminology as Topic
keywords: Concussion; Head injuries; Neurology; Sporting injuries; Trauma surgery